Oxidation behavior of WC-Co

The high temperature oxidation behavior of WC-Co samples has been investigated. The oxidation rate of WC-Co was found to increase rapidly with temperature above 600 degrees C and with the oxygen content of the atmosphere. Increasing the Co content led to an improvement in the oxidation behavior. In all cases, only WO3 and CoWO4 phases were present in the oxide. Although the morphology of the two oxide phases depended on the oxidation conditions, their volume fractions were determined solely by the Co content of the sample. The WO3 formed during the initial stages of oxidation, changed from a strong {001} texture at 600 degrees C to a weak {200} texture at 800 degrees C. As the flow rate of the oxidizing gas was increased, the oxidation rate of WC-Co increased at lower flow rates due to an increase in the oxygen supply to the oxide/sample interface. However, at higher flow rates, the oxidation rates decreased with increasing flow rate.